Inside the VLT Yepun Telescope

Fish-eye view of the interior of Yepun, the fourth of the VLT's 8.2-metre Unit Telescopes (UTs). The white structure visible at the centre is the cell which supports the 8.2-metre primary mirror (M1). The instrument attached below the M1 cell, at the Cassegrain focus, is a near-infrared (1–2.5 μm) integral field spectrograph, SINFONI. The four UTs of the VLT are identical in design and housed in compact, thermally controlled buildings, which rotate synchronously with the telescopes. Each UT works with two or three highly specialised instruments.